1. Field of the Invention
This invention relates generally to a design of lung devices for safely performing a transthoracic procedure. In particular, the invention provides devices and methods of using these devices to access the thoracic cavity with minimal risk of causing pneumothorax or hemothorax. More specifically, the invention enables diagnostic and therapeutic access to a thoracic cavity using large bore instruments. This invention also provides a method for diagnostic and therapeutic procedures using a device capable of sealing the wound upon withdrawal of the device.
2. Description of Related Art
Pulmonary disorders affect millions of Americans, and many more individuals worldwide, each year. While some pulmonary disorders are chronic (e.g., chronic obstructive pulmonary disease (COPD)), many are acute and deadly. For example, lung cancer is the leading cause of death attributable to cancer for both men and women. More people die of lung cancer, than die of breast, prostate and colon cancer combined. It is estimated that in the United States alone, over 170,000 new cases of lung cancer are diagnosed each year. Of those people diagnosed with lung cancer, the prognosis is grim: 6 of 10 will die within one year of being diagnosed and between 7 and 8 will die within two years of diagnosis.
Most lung cancers start in the lining of the bronchi (plural for bronchus), although lung cancer can start in other parts of the lung as well. Since it generally takes many years for lung cancer to develop, there can be areas of pre-cancerous changes in the lung long before the formation of lung cancer. With currently available technology, the pre-cancerous changes are often not detected because the changes cannot be seen on an x-ray and do not cause symptoms early on that would cause a patient to seek medical attention. It is for this reason that most people with lung cancer are not diagnosed during the critical early stages of the disease.
Taking chest x-rays and checking sputum under a microscope for the appearance of cancer cells had been performed for screening but was found to be unreliable, and thus is not even recommended screening for persons of high risk (e.g., those people who smoke). Recently, spiral CT scanning has shown promise as a potential screening tool for finding lung cancer at an early stage. However, at this juncture it is not known whether the use of spiral CT scans improve the prognosis for long-term survival by increasing the early detection of the disease. Even with a scan indicating the possible presence of pre-cancerous tissue, the ability to take a biopsy for testing is difficult without causing the lungs to collapse, which can result in a required hospital stay.
Thus, with the current state of the art, any time a procedure requires an instrument to be inserted through an incision in the chest wall, the pleural layers surrounding the lung are pierced or compromised. As a result of the propensity for transthoracic procedures to cause, for example, pneumothorax, there is a limitation on the outer diameter of the instruments that are used for these procedures. This is a significant drawback for procedures such as percutnaeous transthoracic lung tissue biopsy, where the interventionalist introduces a biopsy needle through the chest wall. Other procedures which are limited when applied to transthoracic procedures include percutaneous transthoracic needle aspiration (PTNA), mediastinoscopy, thorascopy and drainage of pleural effusions. Air leaks and bleeding frequently occur either during insertion or removal of the device through the opening in the pleural lining of the chest cavity. Even when using small needles of 19-23 gauge, the incidence of pneumothorax is relatively high, being in the range of 30-40% and the incidence of hemothorax is 25%. For this reason, larger bore instruments (e.g., having a gauge of less than 19 and therefore a larger diameter) are not typically used to access the lung through the chest cavity, and practitioners are substantially limited in the amount of tissue accessible or treatable using a percutaneous procedure. More importantly, practitioners do not fully benefit from minimally invasive techniques commonly used for diagnostic and therapeutic procedures that are easily performed in other areas of the body (e.g., the breast), when treating the lung.
Treatment options for pneumothorax or hemothorax include intubation, wherein a tube is inserted through the chest wall into the pleural space to withdraw the air or fluid. In that instance, the tube is typically left in place and attached to a drainage system for several days, which requires the patient to be hospitalized. In some circumstances, such as where bleeding occurs, surgical intervention may be required.
Even during the biopsy process currently practiced, multiple samples or cores of tissue are taken through the smallest gauge needle possible in an effort to increase biopsy efficacy while decreasing the likelihood of, for example, pneumothorax. However, each time the needle is reinserted, the chances for pneumothorax or bleeding increase. Additionally, due to the small size of the multiple samples, the pathologist does not have the benefit of a larger sample size that would improve the accuracy of diagnosis.
Thus, there exists a considerable need for devices and methods that provide minimally invasive access to the lung for diagnostics and treatment but which do not risk causing the lung to collapse, or air or blood entering the pleural space. Additionally, what is needed is a tool that enables potentially cancerous tissue to be removed (e.g., for a biopsy) but which prevents cells from migrating along the tract used by the tool to access the tissue. The present invention satisfies these need and provides related advantages as well.